Hard-tissue implant comprising a bulk implant, a face, pillars, slots, and at least one support member

ABSTRACT

Hard-tissue implants are provided that include a bulk implant, a face, pillars, slots, and at least one support member. The pillars are for contacting a hard tissue. The slots are to be occupied by the hard tissue. The at least one support member is for contacting the hard tissue. The hard-tissue implant has a Young&#39;s modulus of elasticity of at least 3 GPa, and has a ratio of the sum of (i) the volumes of the slots to (ii) the sum of the volumes of the pillars and the volumes of the slots of 0.40:1 to 0.90:1. Methods of making and using hard-tissue implants are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.16/492,285, filed Sep. 9, 2019, which is a national stage application ofInternational Application PCT/US2018/021499, filed Mar. 8, 2018, whichclaims the benefit of U.S. Provisional Application No. 62/469,727, filedMar. 10, 2017, all of which are incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to hard-tissue implants, and more particularly tohard-tissue implants that include a bulk implant, a face, pillars,slots, and at least one support member.

BACKGROUND OF THE INVENTION

Conventional hard-tissue implants include implants designed to promotein-growth of hard tissue based on forming a tissue/implant interface inwhich the implant forms a continuous phase and the tissue forms adiscontinuous phase, e.g. based on the implant having a concave and/orporous surface into which the hard tissue can grow, and designed to haveadd-on surface modifications, e.g. modifications added based onsintering.

For example, Van Kampen et al., U.S. Pat. No. 4,608,052, discloses animplant for use in a human body having an integral attachment surfaceadapted to permit ingrowth of living tissue. The implant surface isdefined by a multiplicity of adjacent, generally concave surface partshaving intersecting, generally aligned rims defining an inner attachmentsurface portion and by a multiplicity of spaced posts projecting fromthe inner attachment surface. Van Kampen also discloses that implantshave been provided with porous surfaces, as described in U.S. Pat. Nos.3,605,123, 3,808,606, and 3,855,638.

Also for example, J. D. Bobyn et al, 150 Clinical Orthopaedics & RelatedResearch 263 (1980), discloses that a pore size range of approximately50 to 400 μm provided an optimal or maximal fixation strength (17 MPa)in the shortest time period (8 weeks) with regard to cobalt-base alloyimplants with powder-made porous surfaces. Specifically, implants werefabricated based on coating cylindrical rods of cast cobalt-base alloywith cobalt base alloy powder in four particle size ranges. The particlesize ranges were as follows: 25 to 45 μm; 45 to 150 μm; 150 to 300 μm;and 300 to 840 μm. The corresponding pore size ranges of the particleswere as follows: 20 to 50 μm; 50 to 200 μm; 200 to 400 μm; and 400 to800 μm, respectively. The particles were then bonded to the rods basedon sintering. All implants were manufactured to have a maximal diameterof 4.5 mm and a length of 9.0 mm. The implants were surgically insertedinto holes in dog femurs and bone ingrowth was allowed to proceed. Aftervarying periods of time (4, 8, or 12 weeks), the maximum force requiredto dislodge the implants was determined. Implants with a pore size lowerthan 50 μm yielded relatively low fixation strengths at all time points,while implants with a pore size higher than 400 μm exhibited relativelyhigh scatter with regard to fixation strengths, thus indicating that apore size range of approximately 50 to 400 μm provided an optimal ormaximal fixation strength.

Conventional hard-tissue implants also include implants having surfacetexturing, e.g. raised portions and indented portions, barbs, and/orpillars, to promote an interference fit between the implants andadjacent bone, to make it difficult to withdraw the implants from hardtissue, or to more effectively mechanically anchor at an early date oraffix into adjoining hard tissue.

For example, Tuke et al., U.K. Pat. Appl. No. GB2181354A, discloses anorthopedic implant having at least one surface area, integral with theadjacent portion of the implant and adapted in use to contact bone. Thesurface area has a finely patterned conformation composed of a pluralityof raised portions separated from each other by indented portions. Theindented portions are of a width and depth to allow bone penetrationthereinto in use to promote an interference fit between the implant andadjacent bone in the region of the patterned area.

Also for example, Amrich et al., U.S. Pat. No. 7,018,418, disclosesimplants having a textured surface with microrecesses such that theouter surface overhangs the microrecesses. In one embodiment,unidirectional barbs are produced in the surface that can be insertedinto bone or tissue. The directional orientation of the barbs isintended to make it difficult to withdraw from the bone or tissue.

Also for example, Picha, U.S. Pat. No. 7,556,648, discloses a spinalimplant, i.e. an implant for use in fusing and stabilizing adjoiningspinal vertebrae, including a hollow, generally tubular shell having anexterior lateral surface, a leading end, and a trailing end. Theexterior surface includes a plurality of pillars arranged in anon-helical array. Each pillar has a height of 100 to 4,500 μm and alateral dimension at the widest point of 100 to 4,500 μm. The exteriorsurface also has a plurality of holes therethrough to permit boneingrowth therethrough.

Unfortunately, interfaces of hard tissue and hard-tissue implants inwhich the hard tissue is in a discontinuous phase may be susceptible tostress shielding, resulting in resorption of affected hard tissue, e.g.bone resorption, over time. Also, addition of surface texturing toimplants by sintering can result in the surface texturing occupying anexcessive volume of corresponding hard tissue/implant interfaces,leaving insufficient space for hard tissue. In addition, spinal implantsare designed to perform under conditions relevant to spine, i.e.compression, rotational shear, and vertical shear, with the compressionbeing essentially constant, the rotational shear being intermittent, andthe vertical shear being rare, rather than conditions relevant to otherhard tissues such as long bone, maxillary bone, mandibular bone, andmembranous bone, i.e. load bearing conditions, including compression andtension, varying across the hard tissue and across time, andintermittent rotational and vertical shear.

Picha et al., U.S. Pat. No. 8,771,354, discloses hard-tissue implantsincluding a bulk implant, a face, pillars, and slots. The hard-tissueimplant has a Young's modulus of elasticity of at least 10 GPa, has aratio of (i) the sum of the volumes of the slots to (ii) the sum of thevolumes of the pillars and the volumes of the slots of 0.40:1 to 0.90:1,does not comprise any part that is hollow, and does not comprise anynon-pillar part extending to or beyond the distal ends of any of thepillars. The hard-tissue implants can provide immediate load transferupon implantation and prevent stress shielding over time, thus promotinghard-tissue remodeling and growth at the site of implantation. Theinterface can have a continuous phase corresponding to the hard tissueand a discontinuous phase corresponding to the hard-tissue implant.

Nonetheless, there remains a need for hard-tissue implants of generalapplicability that address the issues discussed above and that provideimprovements. The hard-tissue implant disclosed herein is such animplant.

BRIEF SUMMARY OF THE INVENTION

A hard-tissue implant is provided that includes a bulk implant, a face,pillars, slots, and at least one support member. The face is an exteriorsurface of the bulk implant. The pillars are for contacting a hardtissue. The pillars are distributed on the face, across an area of atleast 30 mm², and extend distally therefrom. Each pillar is integral tothe bulk implant, has a distal end, has a transverse area of (100 μm×100μm) to (10,000 μm×10,000 μm), i.e. 1.0×10⁴ μm² to 1.0×10⁸ μm², and has aheight of 100 to 10,000 μm. The slots are to be occupied by the hardtissue. The slots are defined by the pillars. Each slot has a width of100 to 10,000 μm as measured along the shortest distance betweenadjacent pillars. The at least one support member also is for contactingthe hard tissue. The at least one support member is positioned on theface among the pillars, extends distally from the face, and has atransverse area greater than the transverse area of any of the pillars.The hard-tissue implant has a Young's modulus of elasticity of at least3 GPa, and has a ratio of (i) the sum of the volumes of the slots to(ii) the sum of the volumes of the pillars and the volumes of the slotsof 0.40:1 to 0.90:1.

Also provided is a method of making a hard-tissue implant that, uponimplantation into a hard tissue, provides immediate load transfer andprevents stress shielding. The hard-tissue implant is as describedabove. The method includes designing the hard-tissue implant such thatthe ratio of (i) the product of (a) the Young's modulus of thehard-tissue implant and (b) the sum of the volumes of the pillars to(ii) the product of (a) the Young's modulus of the hard tissue and (b)the sum of the volumes of the slots will be 0.80:1 to 3.8:1. The methodalso includes making the hard-tissue implant.

Also provided is a method of use of a hard-tissue implant in a hardtissue of an individual in need thereof. The hard-tissue implant is asdescribed above. The method includes selecting the hard-tissue implantsuch that the ratio of (i) the product of (a) the Young's modulus of thehard-tissue implant and (b) the sum of the volumes of the pillars to(ii) the product of (a) the Young's modulus of the hard tissue and (b)the sum of the volume of the slots is 0.80:1 to 3.8:1. The method alsoincludes implanting the hard-tissue implant in the hard-tissue.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentdisclosure are better understood when the following detailed descriptionis read with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a hard-tissue implant corresponding to aglenoid implant for shoulder;

FIG. 2 is a perspective view of a hard-tissue implant corresponding to adistal radius plate implant for wrist;

FIG. 3 is a perspective view of a hard-tissue implant corresponding to afemoral capture implant for knee;

FIG. 4 is a perspective view of a hard-tissue implant corresponding to atibial implant for knee;

FIG. 5 is a perspective view of a hard-tissue implant corresponding to atibial implant for ankle;

FIG. 6 is a perspective view of a hard-tissue implant corresponding to atalar implant for ankle;

FIG. 7 is a perspective view of a hard-tissue implant corresponding toan artificial disc implant for spine.

FIG. 8 is a schematic perspective view of a portion of a hard-tissueimplant including pillars;

FIG. 9 is a schematic top plan view of a portion of a hard-tissueimplant including pillars;

FIG. 10 is a schematic side elevational view of a portion of ahard-tissue implant including pillars;

FIG. 11A is a schematic perspective view of a pillar of a hard-tissueimplant;

FIG. 11B is a schematic cross-sectional view of a pillar of ahard-tissue implant;

FIGS. 12A-E are schematic top plan views of portions of hard-tissueimplant including pillars in which the circumference of the transversearea of the pillars thereof have (A) a square shape, (B) a rectangularshape, (C) a herringbone shape, (D) a circular shape, and (E) an ovalshape;

FIG. 13 is a schematic perspective view of part of a portion of ahard-tissue implant including pillars;

FIG. 14 is a top view of the glenoid implant for shoulder of FIG. 1 ;

FIG. 15 is a bottom view of the glenoid implant for shoulder of FIG. 1 ;

FIG. 16 is a side view of the glenoid implant for shoulder of FIG. 1 ;

FIG. 17 is a sectional view of the glenoid implant for shoulder of FIG.14 ;

FIG. 18 is a bottom perspective view of the glenoid implant for shoulderof FIG. 1 ;

FIG. 19 is a top view of the distal radius plate implant for wrist ofFIG. 2 ;

FIG. 20 is a bottom view of the distal radius plate implant for wrist ofFIG. 2 ;

FIG. 21 is a first side view of the distal radius plate implant forwrist of FIG. 2 ;

FIG. 22 is a second side view of the distal radius plate implant forwrist of FIG. 2 ;

FIG. 23 is a third side view of the distal radius plate implant forwrist of FIG. 2 ;

FIG. 24 is a bottom perspective view of the distal radius plate implantfor wrist of FIG. 2 ;

FIG. 25 is a top view of the femoral capture implant for knee of FIG. 3;

FIG. 26 is a bottom view of the femoral capture implant for knee of FIG.3 ;

FIG. 27 is a first side view of the femoral capture implant for knee ofFIG. 3 ;

FIG. 28 is a sectional view of the femoral capture implant for knee ofFIG. 25 ;

FIG. 29 is a second side view of the femoral capture implant for knee ofFIG. 3 ;

FIG. 30 is a third side view of the femoral capture implant for knee ofFIG. 3 ;

FIG. 31 is a sectional view of the femoral capture implant for knee ofFIG. 25 ;

FIG. 32 is a top perspective view of the femoral capture implant forknee of FIG. 3 ;

FIG. 33 is a top view of the tibial implant for knee of FIG. 4 ;

FIG. 34 is a bottom view of the tibial implant for knee of FIG. 4 ;

FIG. 35 is a first side view of the tibial implant for knee of FIG. 4 ;

FIG. 36 is a second side view of the tibial implant for knee of FIG. 4 ;

FIG. 37 is a bottom perspective view of the tibial implant for knee ofFIG. 4 ;

FIG. 38 is a top view of the tibial implant for ankle of FIG. 5 ;

FIG. 39 is a bottom view of the tibial implant for ankle of FIG. 5 ;

FIG. 40 is a first side view of the tibial implant for ankle of FIG. 5 ;

FIG. 41 is a sectional view of the tibial implant for ankle of FIG. 38 ;

FIG. 42 is a second side view of the tibial implant for ankle of FIG. 5;

FIG. 43 is a sectional view of the tibial implant for ankle of FIG. 38 ;

FIG. 44 is a top perspective view of the tibial implant for ankle ofFIG. 5 ;

FIG. 45 is a top view of the talar implant for ankle of FIG. 6 ;

FIG. 46 is a bottom view of the talar implant for ankle of FIG. 6 ;

FIG. 47 is a first side view of the talar implant for ankle of FIG. 6 ;

FIG. 48 is a sectional view of the talar implant for ankle of FIG. 45 ;

FIG. 49 is a second side view of the talar implant for ankle of FIG. 6 ;

FIG. 50 is a sectional view of the talar implant for ankle of FIG. 45 ;

FIG. 51 is a bottom perspective view of the talar implant for ankle ofFIG. 6 ;

FIG. 52 shows results of an expulsion resistance test (Y-axis: expulsionforce (N); X-axis: expulsion displacement (mm)) for implants includingpillars having a pillar height of 2,000 μm and a pillar width of 500 μm,with the implants and pillars being made from materials as follows:metal pillars=titanium alloy Ti-6Al-4V; and plasticpillars=polyetheretherketone (PEEK); and

FIG. 53 shows results of a cage expulsion test (Y-axis: stiffness;X-axis: pillar height), for implants including pillars made from PEEK,each pillar having a pillar width of 500 μm, with pillar heightsexpressed as a multiple of pillar width as follows: 1×=pillar height 500μm; 2×=pillar height 1,000 μm; 3×=pillar height 1,500 μm; and 4×=pillarheight 2,000 μm.

DETAILED DESCRIPTION

As set forth in the figures, example hard-tissue implants are provided.The hard-tissue implants provide advantages, including for example thatthe hard-tissue implants can promote hard-tissue remodeling and growthof the hard tissue at the site of implantation and that the interface ofthe hard-tissue implants and the hard tissue can withstand substantialyield/elongation and load before failure. Without wishing to be bound bytheory, it is believed that these advantages are based on properties ofthe hard-tissue implants and the interface resulting from implantationthereof.

This is because the interface can have a continuous phase correspondingto the hard tissue and a discontinuous phase corresponding to thehard-tissue implant. The hard tissue can also make up at least 40% ofthe volume of the interface, and the product of the Young's modulus ofelasticity of the hard tissue and the volume of the tissue and theproduct of the Young's modulus of elasticity of the implant and thevolume of the pillars of the implant can be well matched. Thus, theinterface can exhibit mechanical properties similar to those of the bulkhard tissue adjacent to the interface. Also, the pillars and the atleast one support member potentially may be pressed into thehard-tissue, e.g. based on tapping during implantation, potentiallyeliminating micro-motion and migration of the implant over time,accommodating torque, and/or eliminating the need for adhesives such ascement or grout to hold the implant in place. In addition, thehard-tissue implants may promote rich vascularization of the hard tissueof the interface, enhancing wound healing, providing nutritionalsupport, accelerating healing, remodeling, and integration of the hardtissue, and limiting the potential for infection of the hard tissue.Rapid or immediate integration of the hard tissue into the space betweenthe pillars of the hard-tissue implant may also prevent detrimentalcellular reactions at the interface, such as formation of fibroustissue, seroma, or thrombosis.

It is believed that implantation of the hard-tissue implant will resultin the pillars and the at least one support member of the hard-tissueimplant contacting the hard tissue. In some cases the pillars and/or theat least one support member may initially penetrate the hard tissue,e.g. partially or completely, upon implantation of the hard-tissueimplant. In such cases, the hard-tissue implants can provide immediateload transfer upon implantation and prevent stress shielding over time,thus promoting hard-tissue remodeling and growth at the site ofimplantation. Alternatively or additionally, in some cases the pillarsand/or the at least one support member may penetrate the hard tissuelater, under physiological loading. Also alternatively or additionally,over time the hard tissue may grow in and around the pillars, thusoccupying slots between the pillars, e.g. during healing.

It also is believed that the hard-tissue implants also provide furtheradvantages in hard-tissue implant applications involving articulation,e.g. for shoulder, wrist, knee, ankle, and spine, because the at leastone support member, in combination with the pillars, can preventpull-out of the hard-tissue implants and further accommodate torque,thus further promoting hard-tissue remodeling and growth at the site ofimplantation.

The interface resulting from implantation of the hard-tissue implantinto the hard tissue will be, or can become, an interface that iscontinuous with respect to the hard tissue and discontinuous withrespect to the hard-tissue implant, across an area of the face of thehard-tissue implant from which the pillars extend. Such an interfacewill further exhibit properties similar to those of the bulk hard tissueadjacent to the interface, e.g. high resilience to load. The result isthat the interface following implantation of a hard-tissue implant intoa hard tissue is surprisingly long-lasting and resilient to load.

As used herein, the term “hard-tissue implant” means an implant suitablefor implantation in a hard tissue. Exemplary hard-tissue implantsinclude a glenoid implant for shoulder, a distal radius plate implantfor wrist, a femoral capture implant for knee, a tibial implant forknee, a tibial implant for ankle, and a talar implant for ankle.Exemplary hard-tissue implants also include an artificial disc implantfor spine.

Exemplary hard tissues suitable for implantation of the hard-tissueimplants include bone, cartilage, calcified cartilage, non-calcifiedcartilage, and tissue that has become mineralized. Exemplary hardtissues also include long bone, maxillary bone, mandibular bone, andmembranous bone. Exemplary hard tissues also include shoulder, femur,tibia, and talus. Exemplary hard tissues also include spine.

As used herein, the term “pillar” means a projection that extendsdistally from a surface of a hard-tissue implant, e.g. from a face ofthe hard-tissue implant, that is not in direct physical contact with anyother pillars or other parts of the implant other than the surface, andthat is for contacting a hard tissue. Because a pillar is not in directphysical contact with any other pillars or other parts of the implantother than the surface, upon implantation no pillar forms a continuousphase within the resulting interface of the hard tissue and hard-tissueimplant. A pillar can have a transverse area, i.e. an area of across-section taken relative to a vertical axis along which the pillarextends distally from the face of the implant, of, for example, (i) (100μm×100 μm) to (10,000 μm×10,000 μm), i.e. 1.0×10⁴ μm² to 1.0×10⁸ μm²,(ii) (200 μm×200 μm) to (2,000 μm×2,000 μm), i.e. 4.0×10⁴ μm² to 4.0×10⁶μm², (iii) (250 μm×250 μm) to (1,000 μm×1,000 μm), i.e. 6.3×10⁴ μm² to1.0×10⁶ μm², (iv) (300 μm×300 μm) to (500 μm×500 μm), i.e. 9×10⁴ μm² to2.5×10⁵ μm², (v) (350 μm×350 μm) to (450 μm×450 μm), i.e. 1.2×10⁵ μm² to2.0×10⁵ μm², or (vi) (395 μm×395 μm) to (405 μm×405 μm), i.e. 1.6×10⁵μm². Of note, the expression of transverse areas of pillars as squaresof linear dimensions, e.g. (100 μm×100 μm), here and throughout thisapplication, is for purposes of convenience only and is not intended tolimit any pillars so described to square shapes, square transverseareas, or square cross-sections. A pillar can have a pillar height, i.e.the height of the pillar from the face of the hard-tissue implant to thedistal end of the pillar, of, for example, 100 to 10,000 μm, 100 to5,000 μm, 200 to 2,500 μm, 300 to 1,000 μm, 400 to 600 μm, 450 to 550μm, 490 to 510 μm, or 500 μm. A pillar can have a volume, i.e. productof pillar transverse area and pillar height, of, for example (i) (100μm×100 μm×100 μm) to (10,000 μm×10,000 μm×10,000 μm), i.e. 1.0×10⁶ μm³to 1.0×10¹² μm³, (ii) (200 μm×200 μm×100 μm) to (2,000 μm×2,000 μm×5,000μm), i.e. 4.0×10⁶ μm³ to 2.0×10¹⁰ μm³, (iii) (250 μm×250 μm×200 μm) to(1,000 μm×1,000 μm×2,500 μm), i.e. 1.3×10⁷ μm³ to 2.5×10⁹ μm³, (iv) (300μm×300 μm×300 μm) to (500 μm×500 μm×1,000 μm), i.e. 2.7×10⁷ μm³ to2.5×10⁸ μm³, (v) (350 μm×350 μm×400 μm) to (450 μm×450 μm×600 μm), i.e.4.9×10⁷ μm³ to 1.2×10⁸ μm³, or (vi) (395 μm×395 μm×490 μm) to (405μm×405 μm×510 μm), i.e. 7.7×10⁷ μm³ to 8.4×10⁷ μm³. A pillar can have,as seen from a top view, a square shape, a rectangular shape, aherringbone shape, a circular shape, or an oval shape, respectively, oralternatively can have other polygonal, curvilinear, or variable shapes.

As used herein, the term “slot” means the spaces between the pillars.Accordingly, the pillars define the slots. The slots can have a slotheight as defined by the pillars, of, for example, 100 to 10,000 μm, 100to 5,000 μm, 200 to 2,500 μm, 300 to 1,000 μm, 400 to 600 μm, 450 to 550μm, or 500 μm. The slots can have a slot width as measured along theshortest distance between adjacent pillars of, for example, 100 to10,000 μm, 100 to 7,500 μm, 100 to 3,000 μm, 150 to 1,000 μm, 175 to 450μm, 190 to 410 μm, 190 to 210 μm, or 390 to 410 μm. The slots have avolume corresponding to the volume of the space between the pillars.

As used herein, the term “support member” means a projection thatextends distally from the face and that has a transverse area greaterthan the transverse area of any of the pillars. Because the supportmember has a transverse area greater than the transverse area of any ofthe pillars, the support member can prevent pull-out of the implants andfurther accommodate torque. The support member can have a distal end.The support member can have a support member height, i.e. the height ofthe support member from the face of the hard-tissue implant to thedistal end of the support member, that is less than, the same as, orgreater than the height of one, many, or all of the pillars. The distalend of the support member can include an opening, e.g. such that thehard-tissue implant has a passage extending from the distal end of thesupport member, through the support member, and through the bulkimplant. Alternatively, the distal end of the support member can lack anopening. The support member can have a support member axial surface. Thesupport member axial surface can be angled with respect to the face ofthe hard-tissue implant, e.g. being generally transverse with respect tothe face of the hard-tissue implant, at 70 to 110 degrees, 80 to 100degrees, or about 90 degrees. The support member can be, for example, arod, a tube, a raised rim surrounding a hole, a fin, or a keel, amongother structures.

As used herein, the term “pore” refers to a void space of less than1,000 μm in size, i.e. having a diameter of less than 1,000 μm, on orbelow a surface, e.g. the surface of a hard-tissue implant. Pores canoccur in a material naturally, e.g. based on a natural porosity of thematerial, or can be introduced, e.g. by chemical or physical treatment.Pores can be continuous with respect to each other, based on beinginterconnected with each other below a surface, or pores can bediscontinuous, based on not being interconnected with each other below asurface. Pores can be sufficiently large to allow for migration andproliferation of osteoblasts and mesenchymal cells. Accordingly, forexample, a porous surface is a surface that includes void spaces of lessthan 1,000 μm in size in the surface, whereas a non-porous surface is asurface that does not include such a void space.

As used herein, the term “interface resulting from implantation of thehard-tissue implant into a hard tissue,” or more simply “interface,”means the product of implantation wherein the pillars of the hard-tissueimplant are contacting a hard tissue and the slots of the hard-tissueimplant are occupied, partially or completely, by the hard tissue. Theinterface includes the pillars, hard tissue that occupies the slots ofthe hard-tissue implant, any remaining unoccupied space in the slots,any hard tissue that occupies any additional space between the face ofthe implant and a plane defined by the distal ends of the pillars, andany hard tissue that occupies any pores on the face or the pillars.Accordingly, the interface boundaries are the face of the hard tissueimplant, the internal surfaces of any pores on the face, and the bulktissue surrounding interface.

In some example embodiments, e.g. immediately after implanting thehard-tissue implant with at least some penetration of the pillars intothe hard tissue and/or after at least some remodeling and growth of thehard tissue to partially fill in space between the hard-tissue implantand the hard tissue, the pillars are contacting the hard tissue (e.g. atdistal ends of the pillars), and the slots are partially occupied by thehard tissue. In other example embodiments, e.g. immediately afterimplanting the hard-tissue implant with extensive penetration of thepillars into the hard-tissue and/or after extensive remodeling andgrowth of the hard tissue to fill in all space between the hard-tissueimplant and the hard tissue, the pillars are contacting the hard tissue(e.g. at distal ends and lateral surfaces of the pillars), and the slotsare completely occupied by the hard tissue. In other exampleembodiments, the pillars contact the hard tissue over time, based onremodeling and growth of hard tissue in and around the pillars, e.g.during healing.

As used herein, the term “continuous,” when used for example inreference to the hard-tissue of an interface, means that the hard tissueforms a single continuous phase, extending throughout and across theinterface to each boundary of the interface. As used herein, the term“discontinuous,” when used for example in reference to the hard-tissueimplant of an interface, means that the hard-tissue implant does notform such a single continuous phase.

Hard-Tissue Implant

Considering the features of an example hard-tissue implant in moredetail, FIGS. 1-7 provide illustrations in perspective view of variousexample hard-tissue implants 100, corresponding to a glenoid implant forshoulder 1001, a distal radius plate implant for wrist 1002, a femoralcapture implant for knee 1003, a tibial implant for knee 1004, a tibialimplant for ankle 1005, a talar implant for ankle 1006, and anartificial disc implant for spine 1007. Additional views of the glenoidimplant for shoulder 1001 are shown in FIGS. 14-18 . Additional views ofthe distal radius plate implant for wrist 1002 are shown in FIGS. 19-24. Additional views of the femoral capture implant for knee 1003 areshown in FIGS. 25-32 . Additional views of the tibial implant for knee1004 are shown in FIGS. 33-37 . Additional views of the tibial implantfor ankle 1005 are shown in FIGS. 38-44 . Additional views of the talarimplant for ankle 1006 are shown in FIGS. 45-51 .

The hard-tissue implant 100 can be made from a material having a Young'smodulus of elasticity, i.e. a tensile modulus of elasticity, of at least3 GPa, as measured at 21° C. The hard-tissue implant 100 can be made,for example, from one or more materials such as implantable-gradepolyaryletherketone that is essentially unfilled (such asimplantable-grade polyetheretherketone or implantable-gradepolyetherketoneketone), titanium, stainless steel, cobalt-chromiumalloy, titanium alloy (such as Ti-6Al-4V titanium alloy or Ti-6Al-7Nbtitanium alloy), ceramic material (such as silicon nitride (Si3N4)), orimplantable-grade composite material (such as implantable-gradepolyaryletherketone with filler, implantable-grade polyetheretherketonewith filler, implantable-grade polyetheretherketone with carbon fiber,or implantable-grade polyetheretherketone with hydroxyapatite). Specificexamples include (i) implantable-grade polyetheretherketone that isessentially unfilled, which has a Young's modulus of approximately 4GPa, (ii) implantable-grade polyetheretherketone with filler, e.g.carbon-fiber-reinforced implantable-grade polyetheretherketone, whichhas a Young's modulus of elasticity of at least 18 GPa, (iii) titanium,which has a Young's modulus of elasticity of approximately 110 GPa, (iv)stainless steel, which has a Young's modulus of elasticity ofapproximately 200 GPa, (v) cobalt-chromium alloy, which has a Young'smodulus of elasticity of greater than 200 GPa, or (vi) titanium alloy,which has a Young's modulus of elasticity of approximately 105-120 GPa,all as measured at 21° C. The hard-tissue implant 100 also can be made,for example, from one or more hard tissues such as a hard tissueobtained from a human or animal (such as autologous hard tissue,allogenic hard tissue, or xenogeneic hard tissue), human cartilage,animal cartilage, human bone, animal bone, cadaver bone, or corticalallograft. Such hard tissues obtained from a human or animal can have aYoung's modulus of elasticity of, e.g. 4 to 18 GPa. Such hard tissuesobtained from a human or animal can also be treated, in advance ofimplantation, to decrease or eliminate the capacity of the hard tissueto elicit an immune response in an individual upon implantation into theindividual. The hard-tissue implant 100 also can be made, for example,from one or more materials such as resin for rapid prototyping, SOMOS®NanoTool non-crystalline composite material, SOMOS® 9120 liquidphotopolymer, SOMOS® WaterShed XC 11122 resin, ACCURA® XTREME™ White 200plastic, or ACCURA® 60) plastic. The hard-tissue implant 100 also can bemade from further combinations of the above-noted materials and/or hardtissues. Accordingly, the hard-tissue implant 100 has a Young's modulusof elasticity of at least 3 GPa, for example 18 to 230 GPa, 18 to 25GPa, 100 to 110 GPa, 190 to 210 GPa, 200 to 230 GPa, 105 to 120 GPa, or4 to 18 GPa.

As shown in FIGS. 1-7 , the hard-tissue implant 100 includes a bulkimplant 110, a face 120, pillars 140, slots 150, and at least onesupport member 180.

Considering the bulk implant 110 in more detail, as shown in FIG. 8 ,the bulk implant 110 forms the core of the hard-tissue implant 100 andcan have a three-dimensional rectangular prism shape, although cuboidal,cylindrical, pyramidal, conical, and other three-dimensional shapes maybe used in further examples. The bulk implant 110 can be made from oneor more of the materials or hard tissues noted above with respect to theimplant 100, e.g. one or more materials such as implantable-gradepolyaryletherketone that is essentially unfilled (such asimplantable-grade polyetheretherketone or implantable-gradepolyetherketoneketone), titanium, stainless steel, cobalt-chromiumalloy, titanium alloy (such as Ti-6Al-4V titanium alloy or Ti-6Al-7Nbtitanium alloy), ceramic material (such as silicon nitride (Si3N4)), orimplantable-grade composite material (such as implantable-gradepolyaryletherketone with filler, implantable-grade polyetheretherketonewith filler, implantable-grade polyetheretherketone with carbon fiber,or implantable-grade polyetheretherketone with hydroxyapatite), or e.g.one or more hard tissues such as a hard tissue obtained from a human oranimal (such as autologous hard tissue, allogenic hard tissue, orxenogeneic hard tissue), human cartilage, animal cartilage, human bone,animal bone, cadaver bone, or cortical allograft, or e.g. one or morematerials such as resin for rapid prototyping, SOMOS® NanoToolnon-crystalline composite material, SOMOS® 9120 liquid photopolymer,SOMOS® WaterShed XC 11122 resin, ACCURA® XTREME™ White 200 plastic, orACCURA® 60) plastic.

The bulk implant 110 can be porous or non-porous. For example, the bulkimplant 110 can include one or more surfaces that are porous, and/or canbe made from one or more materials that are porous. Such porous surfacescan include pores having diameters of, e.g. 1 to 900 μm, 100 to 800 μm,or 200 to 600 μm. Also for example, the bulk implant 110 can includeonly surfaces that are non-porous, and/or can be made only from one ormore materials that are non-porous.

Considering now the face 120 in more detail, as shown in FIG. 1 and FIG.8 , the face 120 of the hard-tissue implant 100 is an exterior surfaceof the bulk implant 110, having a total area 160, not including areaoccupied by the at least support member 180. As shown in FIG. 8 , theface 120 can be flat, i.e. have a flat contour. Alternatively, the face120 can be cylindrical, i.e. have a cylindrical contour. As furtheralternatives, the face 120 can have other angular, curvilinear, and/orirregular contours. The face 120 can have a rectangular peripheral shapeas seen from a top view, although other polygonal, curvilinear, or othershapes may be used in further examples. As shown in FIG. 8 , the facecan be defined by an edge 130. For example, the edge 130 can be a singlecontinuous edge that defines the face 120. Also for example, the edge130 can be two edges that are discontinuous with respect to each otherthat together define the face 120. Also for example, the edge 130 can bethree or more edges that are discontinuous with respect to each otherthat together define the face 120. As shown in FIG. 8 , the edge 130 andthe pillars 140 closest to the edge 130 can define a peripheral border122 of the face 120. As shown in FIG. 1 , the edge 130 can include araised wall 123 that extends above the face 120, such that the face 120is recessed with respect to the raised wall 123. As shown in FIG. 8 ,the edge 130 can define an intersection between the face 120 and one ormore adjacent faces 124 of the hard-tissue implant 100. The face 120 andthe one or more adjacent faces 124 may intersect at the edge 130 at aright angle, although the face 120 and the one or more adjacent faces124 may also intersect at other angles, e.g. acute angles, obtuseangles, or varying angles. The edge 130 can be sharp, although otherrounded, angular, smooth, and/or irregular edges may be used in furtherexamples. The face 120 can be porous, e.g. including pores havingdiameters of, e.g. 1 to 900 μm, 100 to 800 μm, or 200 to 600 μm, or theface 120 can be non-porous. The bulk implant 110 can include more thanone face 120, e.g. two, three, four, five, or more faces 120.

Considering now the pillars 140 in more detail, the pillars 140 are forcontacting a hard tissue. The hard tissue can be selected, for example,from the group consisting of bone, cartilage, calcified cartilage,non-calcified cartilage, and tissue that has become mineralized. Thehard tissue can also be selected, for example, from the group consistingof long bone, maxillary bone, mandibular bone, and membranous bone. Thehard tissue can also be selected, for example, from the group consistingof shoulder, femur, tibia, and talus. The hard tissue can also be, forexample, spine. In some examples, the pillars 140 may contact a hardtissue immediately upon implantation, e.g. based on extending distallyfrom a face 120 of the hard-tissue implant 100. In some examples, thepillars 140 may contact a hard tissue over time after implantation, e.g.based on remodeling and growth of a hard tissue to come in contact withpillars 140 for which distal ends 430 of the pillars 140 are recessedrelative to a surrounding surface of the hard-tissue implant 100.

As shown in FIG. 9 , the pillars 140 are distributed on the face 120 ofthe hard-tissue implant 100, across an area 170 of the face 120 of atleast 30 mm². For example, the pillars 140 can be distributed in aregular pattern 310 on the face 120 of the hard-tissue implant 100,across the area 170 of the face 120. In this regard, the pillars 140 canbe distributed in even rows along a horizontal axis 320 and a verticalaxis 330 of the face 120, and can be distributed along a given rowuniformly with respect to the distances between the centers 142 of thepillars 140 in the row. Also for example, the pillars 140 can also bedistributed in other regular patterns, e.g. the pillars 140 can bedistributed in rows that are even with respect to the horizontal axis320 but not the vertical axis 330, or vice versa, the pillars 140 in onerow may be offset from the pillars 140 in adjacent rows, the pillars 140may be arranged in a spiral pattern, etc. Also for example, the pillars140 can be distributed on the face 120 of the hard-tissue implant 100 inirregular patterns or randomly. For example, the pillars 140 can bedistributed on the face 120 of the hard-tissue implant 100 such that thepillars 140 are packed more densely on one area of the face 120 and lessdensely on another area of the face 120. Moreover, for a bulk implant110 including more than one face 120 across which pillars 140 aredistributed, the pillars 140 can be distributed differently on thevarious faces 120, e.g. in different regular patterns 310, in differentirregular patterns, and/or packed at different densities.

As shown in FIG. 8 and FIG. 9 , the pillars 140 can be distributed onthe face 120 of the hard-tissue implant 100 such that none of thepillars 140 are located at an edge 130, i.e. the face 120 can have aperipheral border 122 that is not occupied by any pillars 140, resultingin the area 170 of the face 120 across which the pillars 140 aredistributed being less than the total area 160 of the face 120. In otherexample embodiments the pillars 140 can be distributed on the face 120of the hard-tissue implant 100 such that at least some of the pillars140 are located at an edge 130, e.g. the area 170 of the face 120 acrosswhich the pillars 140 are distributed can be equal to the total area 160of the face 120.

As shown in FIG. 10 , the pillars 140 extend distally from the face 120of the hard-tissue implant 100. For example, the pillars 140 can extenddistally along a vertical axis 410 from the face 120 of the hard-tissueimplant 100. As shown, the pillars 140 can extend in a uniformdirection, i.e. all pillars 140 extend distally at the same angle withrespect to the face 120 and in the same direction. Also for example,some pillars 140 may extend distally at a different angle and/or in adifferent direction relative to other pillars 140, for example for ahard-tissue implant 100 for which the face 120 is not flat. As alsoshown, the pillars 140 can be perpendicular to the face 120, e.g.extending perpendicularly from the face 120. Also for example, thepillars 140 can extend from the face 120 at other angles and/or varyingangles.

As shown in FIG. 8 , each pillar 140 is integral to the bulk implant110, i.e. the pillars 140 and the bulk implant 110 are made from thesame starting material, rather than, for example, the pillars 140 beingan add-on to the bulk implant 110. Like the bulk implant 110, thepillars 140 can be porous, e.g. including pores having diameters of,e.g. 1 to 900 μm, 100 to 800 μm, or 200 to 600 μm, or the pillars 140can be non-porous.

As shown in FIG. 10 , each pillar 140 has a distal end 430,corresponding to the distal-most portion of the pillar 140 relative tothe face 120 of the hard-tissue implant 100. Each pillar 140 can havedistal edges 432, corresponding to edges defining the distal end 430 ofeach pillar 140. Each pillar 140 can also have lateral edges 434,corresponding to edges of the lateral sides of each pillar 140. Thedistal edges 432 and/or the lateral edges 434 can be sharp, althoughother rounded, angular, smooth, and/or irregular edges may be used infurther examples.

With respect to dimensions of the pillars 140, as shown in FIG. 11A andFIG. 11B, each pillar 140 has a transverse area 510, i.e. an area of across-section taken relative to the vertical axis 410 along which thepillar 140 extends distally from the face 120, of, for example, (i) (100μm×100 μm) to (10,000 μm×10,000 μm), i.e. 1.0×10⁴ μm² to 1.0×10⁸ μm²,(ii) (200 μm×200 μm) to (2,000 μm×2,000 μm), i.e. 4.0×10⁴ μm² to 4.0×10⁶μm², (iii) (250 μm×250 μm) to (1,000 μm×1,000 μm), i.e. 6.3×10⁴ μm² to1.0×10⁶ μm², (iv) (300 μm×300 μm) to (500 μm×500 μm), i.e. 9×10⁴ μm² to2.5×10⁵ μm², (v) (350 μm×350 μm) to (450 μm×450 μm), i.e. 1.2×10⁵ μm² to2.0×10⁵ μm², or (vi) (395 μm×395 μm) to (405 μm×405 μm), i.e. 1.6×10⁵μm². As shown in FIG. 10 and FIG. 11B, each pillar 140 has a pillarheight 420, i.e. the height of the pillar 140 from the face 120 of thehard-tissue implant 100 to the distal end 430 of the pillar 140, of, forexample, 100 to 10,000 μm, 100 to 5,000 μm, 200 to 2,500 μm, 300 to1,000 μm, 400 to 600 μm, 450 to 550 μm, 490 to 510 μm, or 500 μm. Asshown in FIG. 11A, each pillar 140 has a volume 520, i.e. product ofpillar transverse area 510 and pillar height 420, of, for example (i)(100 μm×100 μm×100 μm) to (10,000 μm×10,000 μm×10,000 μm), i.e. 1.0×10⁶μm³ to 1.0×10¹² μm³, (ii) (200 μm×200 μm×100 μm) to (2,000 μm×2,000μm×5,000 μm), i.e. 4.0×10⁶ μm³ to 2.0×10¹⁰ μm³, (iii) (250 μm×250 μm×200μm) to (1,000 μm×1,000 μm×2,500 μm), i.e. 1.3×10⁷ μm³ to 2.5×10⁹ μm³,(iv) (300 μm×300 μm×300 μm) to (500 μm×500 μm×1,000 μm), i.e. 2.7×10⁷μm³ to 2.5×10⁸ μm³, (v) (350 μm×350 μm×400 μm) to (450 μm×450 μm×600μm), i.e. 4.9×10⁷ μm³ to 1.2×10⁸ μm³, or (vi) (395 μm×395 μm×490 μm) to(405 μm×405 μm×510 μm), i.e. 7.7×10⁷ μm³ to 8.4×10⁷ μm³. As shown inFIG. 1 and FIG. 8 , the pillars 140 extending from the face 120 can, forexample, all have identical dimensions, e.g. identical pillar transverseareas 510, pillars heights 420, and thus identical individual volumes.Alternatively, as shown in FIG. 3 , one or more pillars 140 can havedimensions that differ from those of other pillars 140, such that thepillar transverse areas 510 and/or pillar heights 420, and thus volumes,of the one or more pillars 140 differ from those of the other pillars140. As shown in FIG. 1 , for a hard-tissue implant 100 that includes araised wall 123, the pillar height 420 can be the same as a height ofthe raised wall 123, or alternatively the pillar height 420 can be lessthan, greater than, or variable with respect to, a height of the raisedwall 123.

Turning to FIG. 12A to FIG. 12E, the pillars 140 can have, as seen froma top view, a square shape, a rectangular shape, a herringbone shape, acircular shape, or an oval shape, or alternatively can have otherpolygonal, curvilinear, or variable shapes. For example, in someembodiments all pillars 140 can have the same shape, e.g. a squareshape, a rectangular shape, a herringbone shape, a circular shape, or anoval shape, as seen from a top view. Also for example, in someembodiments not all pillars 140 have the same shape as seen from a topview.

Considering now the slots 150 in more detail, the slots 150 are to beoccupied by the hard tissue. For example, upon implantation of thehard-tissue implant 100 into a hard tissue, the hard tissue canimmediately occupy all or part of the space corresponding to the slots150. This can be accomplished, for example, by pressing the hard-tissueimplant 100 into the hard tissue. Moreover, to the extent that the hardtissue does not, upon implantation, immediately occupy all of the spacecorresponding to slots 150, the hard tissue can eventually occupy all orpart of the space corresponding to the slots 150 based on remodelingand/or growth of the hard tissue over time, e.g. during healing.

As shown in FIG. 8 , FIG. 9 , and FIG. 10 , the pillars 140 define theslots 150 therebetween, i.e. the slots 150 are the spaces between thepillars 140. Accordingly, as shown in FIG. 10 , the slots 150 have aslot height 440 as defined by the pillars 140, of, for example, 100 to10,000 μm, 100 to 5,000 μm, 200 to 2,500 μm, 300 to 1,000 μm, 400 to 600μm, 450 to 550 μm, or 500 μm. As shown in FIG. 12A to FIG. 12E, theslots 150 have a slot width 152 as measured along the shortest distancebetween adjacent pillars 140 of, for example, 100 to 10,000 μm, 100 to7,500 μm, 100 to 3,000 μm, 150 to 1,000 μm, 175 to 450 μm, 190 to 410μm, 190 to 210 μm, or 390 to 410 μm. The slots 150 have a volume 710corresponding to the volume of the space between the pillars 140.

Considering now the at least one support member 180 in more detail, asshown in FIG. 1 , the at least one support member 180 also is forcontacting the hard tissue. The hard tissue can be a hard tissue asdiscussed above.

The at least one support member 180 is positioned on the face 120 of thehard-tissue implant 100 among the pillars 140, extending distally fromthe face 120, and having a transverse area 182 greater than thetransverse area 510 of any of the pillars 140.

The at least one support member 180 can have a distal end 184. The atleast one support member 180 can have a support member height 186, i.e.the height of the at least one support member 180 from the face 120 ofthe hard-tissue implant 100 to the distal end 184 of the at least onesupport member 180, that is less than, the same as, or greater than theheight 420 of one, many, or all of the pillars 140. The distal end 184of the at least one support member 180 can include an opening, e.g. suchthat the hard-tissue implant 100 has a passage extending from the distalend 184 of the at least one support member 180, through the at least onesupport member 180, and through the bulk implant 110. Alternatively, thedistal end 184 of the at least one support member 180 can lack anopening. The at least one support member 180 can have a support memberaxial surface 188. The support member axial surface 188 can be angledwith respect to the face 120 of the hard-tissue implant 100, e.g. beinggenerally transverse with respect to the face 120 of the hard-tissueimplant 100, at an angle of 70° to 110°, 80° to 100°, or about 90°. Theat least one support member 180 can be, for example, a rod, a tube, araised rim surrounding a hole, a fin, or a keel, among other structures.

In accordance with some embodiments, the at least one support member 180includes at least two support members 180. For example, the at least onesupport member 180 can include two, three, four, or more support members180.

In accordance with some embodiments, the at least one support member 180is integral to the bulk implant 110, i.e. the at least one supportmember 180 and the bulk implant 110 are made from the same startingmaterial, rather than, for example, the at least one support member 180being an add-on to the bulk implant 110. Like the bulk implant 110, theat least one support member 180 can be porous, e.g. including poreshaving diameters of, e.g. 1 to 900 μm, 100 to 800 μm, or 200 to 600 μm,or the at least one support member 180 can be non-porous.

In accordance with some embodiments, the support member axial surface188 can include support member pillars 190 extending therefrom, e.g.support member pillars 190 like the pillars 140 described above,distributed across all or part of the support member axial surface 188.As will be appreciated, for hard-tissue implants 100 that include atleast one support member 180 that includes a support member axialsurface 188 that is angled with respect to the face 120 of thehard-tissue implant 100, and that further includes support memberpillars 190 extending from the support member axial surface 188, thenthe support member pillars 190 extending from the support member axialsurface 188 can be angled with respect to the pillars 140 extending fromthe face 120 of the hard-tissue implant 100.

Also in accordance with some embodiments, the support member axialsurface 188 can lack pillars, e.g. all or part of the support memberaxial surface 188 can lack pillars. In accordance with theseembodiments, the support member axial surface 188 can be, for example, asmooth surface, a rough surface, a flat surface, a curved surface,and/or an irregular surface, among others.

The hard-tissue implant 100 has a ratio of (i) the sum of the volumes710 of the slots 150 to (ii) the sum of the volumes 520 of the pillars140 and the volumes 710 of the slots 150, of, for example, 0.40:1 to0.90:1, 0.51:1 to 0.90:1, 0.51:1 to 0.60:1, or 0.70:1 to 0.76:1. Withoutwishing to be bound by theory, it is believed that this ratio determinesthe approximate percentages of hard tissue and hard-tissue implant 100that will occupy the interface following implantation of the hard-tissueimplant 100, e.g. that upon pressing the implant 100 into the hardtissue, or upon remodeling and growth of the hard-tissue followingimplantation, that the hard tissue will occupy all or essentially all ofthe space corresponding to the slots 150 of the hard-tissue implant 100.

More specifically, as shown in FIG. 13 , the interface includes (i) thepillars 140, (ii) the slots 150 of the hard-tissue implant 100, whichhave a volume 710 and which, upon or following implantation, becomeoccupied by hard tissue, (iii) any additional space between the face 120of the implant 100 and a plane 720 defined by the distal ends 430 of thepillars 140, e.g. the space between the peripheral border 122 of theface 120 that is not occupied by pillars 140 and the plane 720, whichhas a volume 730 and which also becomes occupied by hard tissue (thusexcluding volume occupied by the support member 180), and (iv) any pores740 on the face 120 or the pillars 140, which, depending on their size,may also become occupied by hard tissue.

Accordingly, for example, a ratio of the sum of (i) the volumes 710 ofthe slots 150 to (ii) the sum of the volumes 520 of the pillars 140 andthe volumes 710 of the slots 150 of 0.40:1 would, following implantationof a hard-tissue implant 100 and subsequent remodeling and growth ofhard tissue, wherein the implant 100 includes an edge 130 and for whichpillars 140 are located at the edge 130, result in an interface thatincludes by volume 40% hard tissue and 60% hard-tissue implant 100, andmore particularly 60% pillars 140 of the hard-tissue implant 100.Similarly, a ratio of (i) the sum of the volumes 710 of the slots 150 to(ii) the sum of the volumes 520 of the pillars 140 and the volumes 710of the slots 150 of 0.40:1 would, following implantation of ahard-tissue implant 100 and subsequent remodeling and growth of hardtissue, wherein the implant 100 includes an edge 130 and for which nopillars 140 are located at the edge 130, result in an interface thatincludes by volume more than 40% hard tissue and less than 60%hard-tissue implant 100, with the percentage of hard tissue increasing,and the percentage of hard-tissue implant 100 decreasing, withincreasing distance between the peripheral-most pillars 140 and slots150 and the edge 130 of the hard-tissue implant 100. By way of furtherexamples, ratios of 0.51:1, 0.60:1, 0.70:1, 0.76:1, and 0.90:1, wouldresult in interfaces that include, by volume, 51% hard tissue and 49%hard-tissue implant 100, 60% hard tissue and 40% hard-tissue implant100, 70% hard tissue and 30% hard-tissue implant 100, 76% hard tissueand 24% hard-tissue implant 100, and 90% hard tissue and 10% hard-tissueimplant, respectively, for a hard-tissue implant 100 wherein the implant100 includes an edge 130 and for which pillars 140 are located at theedge 130. Moreover, the percentage of hard tissue would increase, andthe percentage of hard-tissue implant 100 would decrease, withincreasing distance between the peripheral-most pillars 140 and slots150 and the edge 130 of the hard-tissue implant 100. It is furtherbelieved that by achieving an interface that is at least 40% hardtissue, but that has a sufficient amount of the hard-tissue implant 100to provide support and to keep the implant 100 from migrating, that theinterface will exhibit properties similar to those of the bulk hardtissue adjacent to the interface, e.g. high resilience to load. It alsois believed that by including at least one support member 180 among thepillars 140 that support for the hard-tissue implant 100 will beimproved.

Considering example embodiments of the hard-tissue implant 100 in moredetail, in one example embodiment, the Young's modulus of thehard-tissue implant 100 is 18 to 25 GPa and the ratio of (i) the sum ofthe volumes 710 of the slots 150 to (ii) the sum of the volumes 520 ofthe pillars 140 and the volumes 710 of the slots 150 is 0.51:1 to0.60:1. In another example embodiment, the Young's modulus of thehard-tissue implant 100 is 100 to 110 GPa and the ratio of (i) the sumof the volumes 710 of the slots 150 to (ii) the sum of the volumes 520of the pillars 140 and the volumes 710 of the slots 150 is 0.70:1 to0.76:1. In another example embodiment, the hard-tissue implant 100 ismade of implantable-grade polyetheretherketone with filler, thetransverse area 510 of each pillar 140 is (350 μm×350 μm) to (450 μm×450μm), the pillar height 420 of each pillar 140 is 400 to 600 μm, the slotwidth 152 of each slot 150 is 190 to 210 μm, and the ratio of (i) thesum of the volumes 710 of the slots 150 to (ii) the sum of the volumes520 of the pillars 140 and the volumes 710 of the slots 150 is 0.85:1 to1.6:1. In another example embodiment, the hard-tissue implant 100 ismade of implantable-grade polyetheretherketone with filler, thetransverse area 510 of each pillar 140 is (395 μm×395 μm) to (405 μm×405μm), the pillar height 420 of each pillar 140 is 490 to 510 μm, the slotwidth 152 of each slot 150 is 190 to 210 μm, and the ratio of (i) thesum of the volumes 710 of (ii) the slots 150 to the sum of the volumes520 of the pillars 140 and volumes 710 of the slots 150 is 0.92:1 to1.4:1. In another example embodiment, the hard-tissue implant 100 ismade of titanium, the transverse area 510 of each pillar 140 is (350μm×350 μm) to (450 μm×450 μm), the pillar height 420 of each pillar 140is 400 to 600 μm, the slot width 152 of each slot 150 is 390 to 410 μm,and the ratio of (i) the sum of the volumes 710 of the slots 150 to (ii)the sum of the volumes 520 of the pillars 140 and the volumes 710 of theslots 150 is 2.2:1 to 3.7:1. In another example embodiment, thehard-tissue implant 100 is made of titanium, the transverse area 510 ofeach pillar 140 is (395 μm×395 μm) to (405 μm×405 μm), the pillar height420 of each pillar 140 is 490 to 510 μm, the slot width 152 of each slot150 is 390 to 410 μm, and the ratio of (i) the sum of the volumes 710 ofthe slots 150 to (ii) the sum of the volumes 520 of the pillars 140 andthe volumes 710 of the slots 150 is 2.4:1 to 3.5:1.

With reference to FIG. 1 , the glenoid implant for shoulder 1001exemplifies a hard-tissue implant 100 in which the support member 180has (1) a support member height 186 that is greater than the height 420of all of the pillars 140, (2) a support member axial surface 188 thatis angled with respect to the face 120 of the hard-tissue implant 100,e.g. being generally transverse with respect to the face 120 of thehard-tissue implant 100, and (3) a support member axial surface 188 thatincludes support member pillars 190 extending therefrom, distributedacross all or part of the support member axial surface 188. The glenoidimplant for shoulder 1001 also exemplifies a hard-tissue implant 100 inwhich the edge 130 includes a raised wall 123 that extends above theface 120, such that the face 120 is recessed with respect to the raisedwall 123, and (2) the pillar height 420 is the same as a height of theraised wall 123.

With reference to FIG. 2 , the distal radius plate implant for wrist1002 exemplifies a hard-tissue implant 100 in which the support member180 has (1) a support member height 186 that is the approximately thesame as the height 420 of all of the pillars 140, (2) a support memberaxial surface 188 that is angled with respect to the face 120 of thehard-tissue implant 100, e.g. being generally transverse with respect tothe face 120 of the hard-tissue implant 100, and (3) a support memberaxial surface 188 that lacks pillars. The distal radius plate implantfor wrist 1002 also exemplifies a hard-tissue implant 100 including morethan one support member 180. In this case each support member 180corresponds to a raised rim surrounding a hole, for screws. The distalradius plate implant for wrist 1002 also exemplifies a hard-tissueimplant 100 in which the edge 130 includes a raised wall 123 thatextends above the face 120, such that the face 120 is recessed withrespect to the raised wall 123, and (2) the pillar height 420 is thesame as a height of the raised wall 123.

With reference to FIG. 3 , the femoral capture implant for knee 1003exemplifies a hard-tissue implant 100 in which the support member 180has (1) a support member height 186 that is greater than the height 420of all of the pillars 140, (2) a support member axial surface 188 thatis angled with respect to the face 120 of the hard-tissue implant 100,e.g. being generally transverse with respect to the face 120 of thehard-tissue implant 100, and (3) a support member axial surface 188 thatlacks pillars. The femoral capture implant for knee 1003 alsoexemplifies a hard-tissue implant 100 in which one or more pillars 140have dimensions that differ from those of other pillars 140, such thatthe pillar transverse areas 510 and/or pillar heights 420, and thusvolumes, of the one or more pillars 140 differ from those of the otherpillars 140. The femoral capture implant for knee 1003 also exemplifiesa hard-tissue implant 100 in which the one or more pillars 140 aredistributed peripherally with respect to the face 120 and are intendedfor insertion into cortical bone, and the other pillars 140 aredistributed centrally with respect to the face 120 and are intended forinsertion into cancellous bone.

With reference to FIG. 4 , the tibial implant for knee 1004 exemplifiesa hard-tissue implant 100 in which the support member 180 has (1) asupport member height 186 that is greater than the height 420 of all ofthe pillars 140, (2) a support member axial surface 188 that is angledwith respect to the face 120 of the hard-tissue implant 100, e.g. beinggenerally transverse with respect to the face 120 of the hard-tissueimplant 100, and (3) a support member axial surface 188 that lackspillars. The tibial implant for knee 1004 also exemplifies a hard-tissueimplant 100 in which one or more pillars 140 have dimensions that differfrom those of other pillars 140, such that the pillar transverse areas510 and/or pillar heights 420, and thus volumes, of the one or morepillars 140 differ from those of the other pillars 140. The tibialimplant for knee 1004 also exemplifies a hard-tissue implant 100 inwhich the one or more pillars 140 are distributed peripherally withrespect to the face 120 and are intended for insertion into corticalbone, and the other pillars 140 are distributed centrally with respectto the face 120 and are intended for insertion into cancellous bone.

With reference to FIG. 5 , the tibial implant for ankle 1005 exemplifiesa hard-tissue implant 100 in which the support member 180 has (1) asupport member height 186 that is greater than the height 420 of all ofthe pillars 140, (2) a support member axial surface 188 that is angledwith respect to the face 120 of the hard-tissue implant 100, e.g. beinggenerally transverse with respect to the face 120 of the hard-tissueimplant 100, and (3) a support member axial surface 188 that includessupport member pillars 190 extending therefrom, distributed across allor part of the support member axial surface 188.

With reference to FIG. 6 , the talar implant for ankle 1006 exemplifiesa hard-tissue implant 100 in which the support member 180 has (1) asupport member height 186 that is greater than the height 420 of all ofthe pillars 140, (2) a support member axial surface 188 that is angledwith respect to the face 120 of the hard-tissue implant 100, e.g. beinggenerally transverse with respect to the face 120 of the hard-tissueimplant 100, and (3) a support member axial surface 188 that lackspillars. The talar implant for ankle 1006 also exemplifies a hard-tissueimplant 100 including more than one support member 180. In this case thesupport members 180 correspond to keels.

With reference to FIG. 7 , the artificial disc implant for spine 1007exemplifies a hard-tissue implant 100 in which the support member 180has (1) a support member height 186 that is greater than the height 420of all of the pillars 140, (2) a support member axial surface 188 thatis angled with respect to the face 120 of the hard-tissue implant 100,e.g. being generally transverse with respect to the face 120 of thehard-tissue implant 100, and (3) a support member axial surface 188 thatlacks pillars. The artificial disc implant for spine 1007 alsoexemplifies a hard-tissue implant 100 including more than one supportmember 180. In this case the support members 180 correspond to keels.The artificial disc implant for spine 1007 also exemplifies ahard-tissue implant 100 including more than one face 120 includingpillars 140. The artificial disc implant for spine 1007 also exemplifiesa hard-tissue implant 100 in which the edge 130 includes a raised wall123 that extends above the face 120, such that the face 120 is recessedwith respect to the raised wall 123, and (2) the pillar height 420 isthe same as a height of the raised wall 123.

Methods of Making Hard-Tissue Implants

Methods will now be described for making a hard-tissue implant that,upon implantation into a hard tissue, provides immediate load transferand prevents stress shielding. The hard-tissue implant 100 is asdescribed above.

The method includes a step of designing the hard-tissue implant 100 suchthat the ratio of (i) the product of (a) the Young's modulus of thehard-tissue implant 100 and (b) the sum of the volumes 520 of thepillars 140, to (ii) the product of (a) the Young's modulus of the hardtissue and (b) the sum of the volumes 710 of the slots 150, will be, forexample, 0.80:1 to 3.8:1, 0.90:1 to 3.6:1, 0.85:1 to 1.6:1, 0.92:1 to1.4:1, 2.2:1 to 3.7:1, or 2.4:1 to 3.5:1. Without wishing to be bound bytheory, it is believed that by designing the hard-tissue implant 100 inthis way the interface resulting from implantation of the hard-tissueimplant 100 will have a Young's modulus of elasticity similar to that ofthe bulk hard tissue adjacent to the interface, and again will exhibitproperties similar to those of the bulk hard tissue adjacent to theinterface, e.g. high resilience to load. This step can be carried out,for example by determining the features of the hard-tissue implant 100in view of the particular hard tissue that will be the object ofimplantation. Features to be determined include the material from whichthe hard-tissue implant 100 will be made, the dimensions of the bulkimplant 110 of the hard-tissue implant 100, the area 170 of the face 120of the hard-tissue implant 100 across which pillars 140 will bedistributed, and the number, distribution, size, and direction ofextension of the pillars 140.

The hard tissue can be selected, for example, from the group consistingof bone, cartilage, calcified cartilage, non-calcified cartilage, andtissue that has become mineralized. The hard tissue can also beselected, for example, from the group consisting of long bone, maxillarybone, mandibular bone, and membranous bone. The hard tissue can also beselected, for example, from the group consisting of shoulder, femur,tibia, and talus. The hard tissue can also be, for example, spine. Thehard tissue can also be selected, for example, from spine.

The hard-tissue implant 100 can be made from one or more of thematerials and/or hard tissues as described above. Also, the hard-tissueimplant 100 can include the various example embodiments as disclosedabove.

The Young's modulus of elasticity of the hard-tissue implant 100 can beextrapolated based on that of the materials and/or hard tissues fromwhich the hard-tissue implant 100 is made, or determined experimentally.The Young's modulus of elasticity of the hard tissue can be determined,for example, based on previously determined values for hard tissue ofthat type or based on direct measurement. For example, it has beenreported in the art that wet human femoral bone yields values forYoung's modulus of elasticity, as determined by mechanical testing, asfollows: E_(long) 17 GPa, E_(transv) 11.5, and E_(transv) 11.5. See,e.g., Elastic anisotropy of bone,http://silver.neep.wisc.edu/˜lakes/BME315N3.pdf (last accessed Dec. 8,2010) (citing Reilly, D. T. & Burstein, A. H., The Elastic and UltimateProperties of Compact Bone Tissue, 8 J. Biomechanics 393-405 (1975)). Ithas also been reported in the art that wet bovine femoral bone yieldsvalues for Young's modulus of elasticity, as determined by ultrasound,as follows: E_(long) 22 GPa, E_(transv) 15, and E_(transv) 12. See,e.g., Elastic anisotropy of bone (citing Van Buskirk, W. C. & Ashman, R.B., The Elastic Moduli of Bone, in Mechanical Properties of Bone, JointASME-ASCE Applied Mechanics, Fluids Engineering and BioengineeringConference, Boulder, Colo., 1981). It has also been reported in the artthat the stiffness of compact bone tissue varies with the type of bone,e.g. the Young's moduli of fibular bone and tibial bone are about 18%greater and 7% greater, respectively, than the Young's modulus offemoral bone. See, e.g., Elastic anisotropy of bone.

Additional alternatives for the step of designing the hard-tissueimplant 100 such that the ratio of (i) the product of (a) the Young'smodulus of the hard-tissue implant 100 and (b) the sum of the volumes520 of the pillars 140 to (ii) the product of (a) the Young's modulus ofthe hard tissue and (b) the sum of the volumes 710 of the slots 150 willbe, for example, 0.80:1 to 3.8:1, 0.90:1 to 3.6:1, 0.85:1 to 1.6:1,0.92:1 to 1.4:1, 2.2:1 to 3.7:1, or 2.4:1 to 3.5:1, can include, forexample, use of different materials for making the hard-tissue implant100, selecting different dimensions of the bulk implant 110 of thehard-tissue implant 100, selecting a different area 170 of the face 120of the hard-tissue implant 100 across which pillars 140 will bedistributed, and/or selecting different numbers, distributions, sizes,and directions of extension of the pillars 140. For example, for designof a hard-tissue implant 100 made from a hard tissue, the relatively lowYoung's modulus of elasticity of the hard tissue could be taken intoaccount, such that the hard-tissue implant 100 could be designed toyield an interface, upon implantation into a hard tissue, for which theratio of (i) the sum of the volumes of the slots to (ii) the sum of thevolumes of the pillars and the volumes of the slots is approximately0.50:1 and the ratio of (i) the product of (a) the Young's modulus ofthe hard-tissue implant 100 and (b) the sum of the volumes 520 of thepillars 140 to (ii) the product of (a) the Young's modulus of the hardtissue and (b) the sum of the volumes 710 of the slots 150 will be about1:1. Also for example, for design of a hard-tissue implant 100 forimplantation into a relatively old hard tissue, e.g. a bone of anelderly person, a relative decrease in Young's modulus of elasticityassociated with increasing age of a hard tissue can be taken intoaccount in designing the hard-tissue implant 100.

The method also includes a step of making the hard-tissue implant 100 inaccordance with the design. Methods for making a hard-tissue implant 100as disclosed herein include laser cutting, injection molding, 3Dprinting, and other fabrication methods that are known in the art.

Methods of Using Hard-Tissue Implants

Methods will now be described for use of a hard-tissue implant 100 in ahard tissue of an individual in need thereof. The hard-tissue implant100 is as described above.

The method includes a step of selecting the hard-tissue implant 100 suchthat the ratio of (i) the product of (a) the Young's modulus of thehard-tissue implant 100 and (b) the sum of the volumes 520 of thepillars 140, to (ii) the product of (a) the Young's modulus of the hardtissue and (b) the sum of the volumes 710 of the slots 150, is, forexample, 0.80:1 to 3.8:1, 0.90:1 to 3.6:1, 0.85:1 to 1.6:1, 0.92:1 to1.4:1, 2.2:1 to 3.7:1, or 2.4:1 to 3.5:1.

The method also includes a step of implanting the hard-tissue implant100 in the hard-tissue. The implanting can be done, for example, withoutrotation or twisting of the hard-tissue implant 100. The implanting canalso be done, for example, without use of adhesives, e.g. cement orgrout. The implanting can also be done, for example, without use ofscrews or plating mechanisms.

The implanting can include, for example, pressing the hard-tissueimplant 100 into the hard tissue, thereby providing immediate loadtransfer and preventing stress shielding. The pressing can be, forexample, by direct compression, mechanical compression, or tapping. Suchpressing can include pressing the pillars 140 and the at least onesupport member 180 of the hard-tissue implant 100 into the hard tissue,such that the pillars 140 and the at least one support member 180penetrate into the hard tissue, partially or completely. For example,the hard-tissue implant 100 can be pressed into the hard-tissue suchthat the pillars 140 penetrate the hard-tissue to a depth of, forexample, 1 to 10,000 μm, 100 to 5,000 μm, 200 to 2,500 μm, 300 to 1,000μm, 400 to 600 μm, 450 to 550 μm, 490 to 510 μm, or 500 μm. Also forexample, the hard-tissue implant 100 can be pressed into the hard-tissuesuch that pillars 140 penetrate the hard tissue to a depth, relative tothe pillar height 420 of the pillars 140, of for example 25%, 50%, 75%,and 100% of the pillar height 420 of the pillars 140.

The implanting can also include, for example, pressing the hard-tissueimplant 100 into the hard tissue, such that the pillars 140 are orientedperpendicularly to the primary axis of tension and compression of thehard tissue and penetrate the hard tissue, thereby providing immediateload transfer and preventing stress shielding. The term “primary axis oftension and compression of the hard tissue,” as used herein, means themain axis of the hard tissue along which forces of tension andcompression are transmitted during normal function and use of the hardtissue, e.g. the long axis of a bone such as tibia or femur. Withoutwishing to be bound by theory, it is believed that by having the pillars140 oriented perpendicularly to the primary axis of tension andcompression of the hard tissue, and further by having the pillars 140penetrate the hard tissue during the implanting, that immediatelyfollowing the implanting the hard-tissue implant 100 will experienceimmediate load transfer with respect to tension and compression of thehard tissue, and that this will prevent stress shielding of the hardtissue at the interface of the hard-tissue implant 100 and the hardtissue.

Also for example, the implanting can include pressing the hard-tissueimplant 100 into the hard tissue, such that the pillars 140 are orientedat an acute angle relative to the direction of the pressing andpenetrate the hard tissue, thereby providing immediate load transfer andpreventing stress shielding. By the pillars 140 being oriented at anacute angle relative to the direction of the pressing it is meant thatpillars 140 are angled forward to at least some extent, i.e. are at anangle of less than 90°, relative to the direction of the path by whichthe implant 100 is pressed into the hard tissue. By being oriented at anacute angle, it is meant that a plurality of pillars 140, e.g. at least10%, at least 20%, at least 30%, at least 40%, at least 50%, at least60%, at least 70%, at least 80%, at least 90%, or 100%, are oriented atan acute angle, e.g. at angles ranging from 1° to 89°, 10° to 80°, 20°to 70°, 30° to 60°, 40° to 50°, 1° to 10°, 11° to 20°, 21° to 30°, 31°to 40°, 41° to 50°, 51° to 60°, 61° to 70°, 71° to 80°, 81° to 89°, 15°,30°, 45°, 60°, or 75°, relative to the direction of the pressing.Without wishing to be bound by theory, it is believed that by having thepillars 140 oriented at an acute angle relative to the direction of thepressing, and further by having the pillars 140 penetrate the hardtissue during the implanting, that again immediately following theimplanting the hard-tissue implant 100 will experience immediate loadtransfer with respect to tension and compression of the hard tissue,thereby providing immediate load transfer between the hard-tissueimplant 100 and the hard tissue, and that this will prevent stressshielding of the hard tissue at the interface of the hard-tissue implant100 and the hard tissue.

Also for example, the implanting can include pressing the hard-tissueimplant 100 into a cavity that has been milled in the hard tissue, suchthat the pillars 140 penetrate the hard tissue, thereby providingimmediate load transfer and preventing stress shielding. For example,the cavity can be milled to dimensions wider than that of the bulkimplant 110 but narrower than the bulk implant 110 including the pillars140, such that the pressing of the hard-tissue implant 100 into thecavity results in the pillars 140 of the hard-tissue implant 100contacting and penetrating the hard tissue during the pressing. Also forexample, the cavity that has been milled in the hard tissue can betapered from the surface of the hard tissue inward, i.e. wider at thesurface of the hard tissue and narrower with increasing depth in thehard tissue, such that the pressing of the hard-tissue implant 100 intothe cavity results in the pillars 140 of the hard-tissue implant 100contacting and penetrating the hard tissue only after the implant 100has been pressed to some depth in the cavity. Also for example, thehard-tissue implant 100 can be tapered, such that a tapered cavity and atapered hard-tissue implant 100 have a complementary fit, e.g. such thatpressing of the hard-tissue implant 100 into the cavity results in thepillars 140 of the hard-tissue implant 100 contacting and penetratingthe hard tissue only after the implant 100 has been pressed to somedepth in the cavity at each area of complementary fit between thetapered cavity and the tapered hard-tissue implant 100. Without wishingto be bound by theory, it is believed that by pressing the hard-tissueimplant 100 into a cavity that has been milled in the hard tissue, suchthat the pillars 140 penetrate the hard tissue during the implanting,that again immediately following the implanting the hard-tissue implant100 will experience immediate load transfer with respect to tension andcompression of the hard tissue, and that this will prevent stressshielding of the hard tissue at the interface of the hard-tissue implant100 and the hard tissue.

In some embodiments, additional hard tissue can be added to the face 120and/or the pillars 140 of the hard-tissue implant 100 prior toimplanting. For example, shavings of hard-tissue of a patient, generatedduring preparation work including sawing or drilling of hard tissue ofthe patient, can be added. This may promote growth of tissue into slots150 of the hard-tissue implant 100 following implantation.

Also in some embodiments, additional compositions can be added to theface 120 and/or the pillars 140 of the hard-tissue implant 100 prior toimplanting. Such compositions include, for example, blood, one or moreantibiotics, one or more osteogenic compounds, bone marrow aspirate,and/or surface chemistry for inducing early bone ingrowth. For example,the face 120 and/or the pillars 140 can be coated with one or more suchcompositions, with the pillars 140 retaining the compositions duringimplantation. This also may promote growth of tissue into slots 150 ofthe hard-tissue implant 100 following implantation.

Standard approaches for implanting the hard-tissue implant 100, pressingthe hard-tissue implant 100 into hard tissue, orienting the hard-tissueimplant 100 or pillars 140 thereof, and pressing the hard-tissue implant100 into a cavity that has been milled in the hard tissue are known inthe art and can be used in the methods disclosed here.

The hard tissue can be selected, for example, from the group consistingof bone, cartilage, calcified cartilage, non-calcified cartilage, andtissue that has become mineralized. The hard tissue can also beselected, for example, from the group consisting of long bone, maxillarybone, mandibular bone, and membranous bone. The hard tissue can also beselected, for example, from the group consisting of shoulder, femur,tibia, and talus. The hard tissue can also be, for example, spine. Thehard tissue can also be selected, for example, from spine.

The method can be applied to example embodiments of the hard-tissueimplant 100 as disclosed above. The ratio of (i) the sum of the volumes710 of the slots 150 to (ii) the sum of the volumes 520 of the pillars140 and the volumes 710 of the slots 150 can be determined essentiallyas described above with respect to designing the hard-tissue implant100. The ratio of (i) the product of (a) the Young's modulus of thehard-tissue implant 100 and (b) the sum of the volumes 520 of thepillars 140, to (ii) the product of (a) the Young's modulus of the hardtissue and (b) the sum of the volumes 710 of the slots 150, can also bedetermined essentially as described above with respect to designing thehard-tissue implant 100.

EXAMPLES

Pillar Design Variation and Underlying Anatomic Structures

A theory for variation of pillar design based on underlying anatomicalstructures is presented. In accordance with the theory, the pillargeometry or pillar material can be varied to produce a desiredstructural response when engaged with surrounding tissue, based on thespecific orthopedic application and underlying anatomy. For example,cancellous bone exhibits a material modulus of approximately 0.04 to 1.0GPa, while cortical bone exhibits a material modulus of approximately12.0 to 25.0 GPa. In some applications it may be desirable and/ornecessary to provide a single implant that can interface with bothcancellous and cortical bone. For example, a tibial tray in a total kneearthrodesis (also termed TKA) may interface at its peripheral surface(s)with cortical bone while interfacing at its central surface(s) withcancellous bone. Also for example, a femoral capture implant for kneemay interface at its peripheral surface(s) with cortical bone whileinterfacing at its central surface(s) with cancellous bone. To elicitthe desired response and interaction between the implant and tissue,i.e. underlying cortical and cancellous bone, implant material and/orpillar geometry can be varied to provide the desired interfaceproperties.

While the gross material properties (material modulus) define theresponse of the bulk material, the structural response of the specificdesign parameters can also affect the mechanical response of the pillarsat the interface.

Consider, for example, two pillars, both having a width of 500 μm and aheight of 2,000 μm, but having been made from two different implantmaterials, e.g. a metal corresponding to titanium alloy Ti-6Al-4V and aplastic corresponding to polyetheretherketone (PEEK). The modulus oftitanium alloy Ti-6Al-4V is approximately 110 GPa, whereas the materialmodulus of PEEK is approximately 4.1 GPa. Given the same pillargeometry, the structural stiffness of the pillars will be much greaterin titanium than PEEK.

Consider also two pillars made from the same material but differentlysized, e.g. a first pillar having a width of 500 μm and a height of 500μm, and a second pillar having a width of 500 μm and a height of 2,000μm. While the two pillars have been made from the same base materialwith the same gross material properties, the two pillars will have verydifferent structural stiffnesses in bending due to their differentgeometries. The taller pillars will be less stiff than the shorterpillars.

Now, considering the interface between the tissue, i.e. again underlyingcortical and cancellous bone, and the implant, it is believed that it isadvantageous to closely match the structural stiffness of the pillargeometry with the compliance of the underlying tissue, as indicated bythe material modulus of the underlying tissue.

For example, an implant, such as a tibial tray in TKA, among others, canbe made including two or more types of pillars, each type of pillarbeing made to have a geometry that will provide a structural stiffnessthat matches the compliance of the underlying tissue with which thattype of pillar will interface. In this example, each type of pillar canbe integral to the implant. One type of pillar can be positioned on oneor more surfaces of the implant to interface with cortical bone, e.g. onone or more peripheral surfaces of the implant. Such pillars can berelatively short and more stiff, to match the compliance of the corticalbone. Another type of pillar can be positioned on one or more surfacesof the implant to interface with cancellous bone, e.g. on one or morecentral surfaces of the implant. Such pillars can be relatively tall andless stiff, to match the compliance of the underlying cancellous bone.Such implants may be made from one material and yet provide two or moretypes of pillars exhibiting different stiffnesses, each type of pillarbeing matched with the compliance of the underlying tissue.

Also for example, an implant, again such as a tibial tray in TKA, amongothers, can be made from two or more types of materials, one or moreharder materials (higher gross material modulus) and one or more softermaterials (lower gross material modulus). The harder material(s) can beused for pillars positioned on one or more surfaces of the implant tointerface with cortical bone, e.g. one or more peripheral surfaces ofthe implant. The softer material(s) can be used for pillars positionedon one or more surfaces of the implant to interface with cancellousbone, e.g. one or more central surfaces of the implant.

Initial experiments have been conducted to test the theory. The initialexperiments were conducted using a constant tissue substitute (15 PCFSawBones biomechanical test material) to simulate bone tissue. Thetissue substitute is a foam. A variety of pillar geometries and implantmaterials were tested in a common test setup (ASTM Draft F-04.25.02.02Static Expulsion) to quantify the interaction between the implants andthe tissue substitute. Specifically, the experiments involved placementof implants between two pieces of tissue substitute, to form a“foam-pillar-foam sandwich,” then measuring resistance to pushout(expulsion) of the implants from between the two pieces of tissuesubstitute.

Results of the initial experiments are provided in FIG. 52 and FIG. 53 .FIG. 52 shows results of an expulsion resistance test for implantsincluding pillars having a pillar height of 2,000 μm and a pillar widthof 500 μm, with the pillars being integral to the implants, and with theimplants and pillars being made from titanium alloy Ti-6Al-4V (metalpillars) or PEEK (plastic pillars). FIG. 53 shows results of a cageexpulsion test for implants including pillars made from PEEK, with thepillars being integral to the implants, each pillar having a pillarwidth of 500 μm, and the pillars having pillar heights of 500 μm (1×),1,000 μm (2×), 1,500 μm (3×), or 2,000 μm (4×).

It was found generally that pillars that are taller and/or made fromsofter material (lower gross material modulus) tended to provide a lessstiff interface (lower force to displacement slope). Pillars that areshorter and/or made from a stronger material (higher gross materialmodulus) tended to provide an increased resistance to pushout(expulsion).

Considering the results in more detail, at early time points followingplacement of the implants between the two pieces of tissue substitute,before the pillars began to become embedded into the tissue substitute,the stiffness response indicated that increasing pillar height resultedin a “softer” stiffness response. At later time points followingplacement of the implants, as the pillars began to become embedded intothe tissue substitute, the stiffness response changed. Pillars of 1,000μm height exhibited increased resistance to pushout relative to pillarsof 500 μm height, as the pillars of 1,000 μm height were strong enoughto dig deeply into the tissue substitute and resist the expulsion force.In contrast, for pillars of 1,500 μm and 2,000 μm heights, the expulsionforce exceeded the collective bending strength of the pillars, and themaximum expulsion force actually decreased because the pillars wouldbend before the pillars could fully embed and carry the greaterexpulsion force. Importantly, it is early time points that areclinically relevant. In vivo, a range of motion of about 0 to 500 μmwould be expected to be relevant. Greater motion would likely be aclinical failure. Within the range of motion of 0 to 500 μm, stiffermaterial pillars provide greater expulsion resistance. Also, there is atrade-off between stiffness and strength. For the height parameter,stiffness is linear with height but there is a height where expulsionresistance is a maximum. Beyond that height, expulsion resistance fallsoff due to pillar bending failure.

EXEMPLARY EMBODIMENTS

The following are exemplary embodiments of the hard-tissue implant, themethod of making the hard-tissue implant, and the method of use of thehard-tissue implant as disclosed herein.

Embodiment A: A hard-tissue implant comprising:

-   -   (a) a bulk implant;    -   (b) a face being an exterior surface of the bulk implant;    -   (c) pillars for contacting a hard tissue, the pillars being        distributed on the face, across an area of at least 30 mm², and        extending distally therefrom, and each pillar being integral to        the bulk implant, having a distal end, having a transverse area        of (100×100) to (10,000×10,000)μm², and having a height of 100        to 10,000 μm;    -   (d) slots to be occupied by the hard tissue, the slots being        defined by the pillars and each slot having a width of 100 to        10,000 μm as measured along the shortest distance between        adjacent pillars; and    -   (e) at least one support member for contacting the hard tissue,        the at least one support member being positioned on the face        among the pillars, extending distally from the face, and having        a transverse area greater than the transverse area of any of the        pillars; wherein:    -   the hard-tissue implant has a Young's modulus of elasticity of        at least 3 GPa, and has a ratio of (i) the sum of the volumes of        the slots to (ii) the sum of the volumes of the pillars and the        volumes of the slots of 0.40:1 to 0.90:1.

Embodiment B: The hard-tissue implant of embodiment A, wherein thehard-tissue implant is made of one or more materials selected fromimplantable-grade polyaryletherketone that is essentially unfilled,implantable-grade polyetheretherketone, implantable-gradepolyetherketoneketone, titanium, stainless steel, cobalt-chromium alloy,titanium alloy, Ti-6Al-4V titanium alloy, Ti-6Al-7Nb titanium alloy,ceramic material, silicon nitride (Si3N4), implantable-grade compositematerial, implantable-grade polyaryletherketone with filler,implantable-grade polyetheretherketone with filler, implantable-gradepolyetheretherketone with carbon fiber, or implantable-gradepolyetheretherketone with hydroxyapatite.

Embodiment C: The hard tissue implant of embodiment A, wherein thehard-tissue implant is made of one or more other hard tissues selectedfrom human hard tissue, animal hard tissue, autologous hard tissue,allogenic hard tissue, xenogeneic hard tissue, human cartilage, animalcartilage, human bone, animal bone, cadaver bone, or cortical allograft.

Embodiment D: The hard tissue implant of embodiment A, wherein thehard-tissue implant is made of one or more materials selected from resinfor rapid prototyping, SOMOS® NanoTool non-crystalline compositematerial, SOMOS® 9120 liquid photopolymer, SOMOS® WaterShed XC 11122resin, ACCURA® XTREME™ White 200 plastic, or ACCURA® 60) plastic.

Embodiment E: The hard-tissue implant of any of embodiments A-D, whereinthe face is flat.

Embodiment F: The hard-tissue implant of any of embodiments A-D, whereinthe face has a cylindrical contour.

Embodiment G: The hard-tissue implant of any of embodiments A-F, whereinthe pillars extend in a uniform direction.

Embodiment H: The hard-tissue implant of any of embodiments A-G, whereinthe pillars are perpendicular to the face.

Embodiment I: The hard-tissue implant of any of embodiments A-H, whereinthe transverse area of each pillar is (250×250) μm² to (1,000×1,000)μm².

Embodiment J: The hard-tissue implant of any of embodiments A-I, whereinthe height of each pillar is 200 to 2,500 μm.

Embodiment K: The hard-tissue implant of any of embodiments A-J, whereinthe width of each slot is 200 to 2,500 μm.

Embodiment L: The hard-tissue implant of any of embodiments A-K, whereinthe Young's modulus of the hard-tissue implant is 18 to 25 GPa and theratio of (i) the sum of the volumes of the slots to (ii) the sum of thevolumes of the pillars and the volumes of the slots is 0.51:1 to 0.60:1.

Embodiment M: The hard-tissue implant of embodiments A-K, wherein theYoung's modulus of the hard-tissue implant is 100 to 110 GPa and theratio of (i) the sum of the volumes of the slots to (ii) the sum of thevolumes of the pillars and the volumes of the slots is 0.72:1 to 0.76:1.

Embodiment N: The hard-tissue implant of any of embodiments A-K, whereinthe hard-tissue implant is made of implantable-gradepolyetheretherketone with filler, the transverse area of each pillar is(350×350) to (450×450) μm², the height of each pillar is 400 to 600 μm,the width of each slot is 190 to 210 μm, and the ratio of the sum of (i)the volumes of the slots to (ii) the sum of the volumes of the pillarsand the volumes of the slots is 0.51:1 to 0.60:1.

Embodiment O: The hard-tissue implant of any of embodiments A-K, whereinthe hard-tissue implant is made of titanium, the transverse area of eachpillar is (350×350) to (450×450) μm², the height of each pillar is 400to 600 μm, the width of each slot is 390 to 410 μm, and the ratio of (i)the sum of the volumes of the slots to (ii) the sum of the volumes ofthe pillars and the volumes of the slots is 0.72:1 to 0.76:1.

Embodiment P: The hard-tissue implant of any of embodiments A-O, whereinthe at least one support member comprises at least two support members.

Embodiment Q: The hard-tissue implant of any of embodiments A-P, whereinthe at least one support member is integral to the bulk implant.

Embodiment R: The hard-tissue implant of any of embodiments A-Q, whereinthe at least one support member comprises a support member axial surfacecomprising support member pillars extending therefrom.

Embodiment S: The hard-tissue implant of any of embodiments A-Q, whereinthe at least one support member comprises a support member axial surfacelacking pillars.

Embodiment T: The hard-tissue implant of any of embodiments A-S, whereinthe bulk implant is non-porous.

Embodiment U: The hard-tissue implant of any of embodiments A-T, whereinthe pillars are non-porous.

Embodiment V: The hard-tissue implant of any of embodiments A-U, whereinthe at least one support member is non-porous.

Embodiment W: The hard-tissue implant of any of embodiments A-V, whereinone or more pillars have dimensions that differ from those of otherpillars, such that the transverse areas and/or heights, and thusvolumes, of the one or more pillars differ from those of the otherpillars.

Embodiment X: The hard-tissue implant of embodiment W, wherein the oneor more pillars are distributed peripherally with respect to the faceand are intended for insertion into cortical bone, and the other pillarsare distributed centrally with respect to the face and are intended forinsertion into cancellous bone.

Embodiment Y: The hard-tissue implant of any of embodiments A-X, whereinthe hard-tissue implant is selected from the group consisting of aglenoid implant for shoulder, a distal radius plate implant for wrist, afemoral capture implant for knee, a tibial implant for knee, a tibialimplant for ankle, a talar implant for ankle, and an artificial discimplant for spine.

Embodiment Z: A method of making the hard-tissue implant of any ofembodiments A-Y, that, upon implantation into a hard tissue, providesimmediate load transfer and prevents stress shielding, the methodcomprising:

(1) designing the hard-tissue implant such that the ratio of (i) theproduct of (a) the Young's modulus of the hard-tissue implant and (b)the sum of the volumes of the pillars to (ii) the product of (a) theYoung's modulus of the hard tissue and (b) the sum of the volumes of theslots will be 0.80:1 to 3.8:1; and

(2) making the hard-tissue implant.

Embodiment AA: A method of use of the hard-tissue implant of any ofembodiments A-Y in a hard tissue of an individual in need thereof, themethod comprising:

-   -   (1) selecting the hard-tissue implant such that the ratio of (i)        the product of (a) the Young's modulus of the hard-tissue        implant and (b) the sum of the volumes of the pillars to (ii)        the product of (a) the Young's modulus of the hard tissue        and (b) the sum of the volumes of the slots is 0.80:1 to 3.8:1;        and    -   (2) implanting the hard-tissue implant in the hard-tissue of the        individual.

It will be apparent to those skilled in the art that variousmodifications and variations can be made without departing from thespirit and scope of the claimed invention.

What is claimed is:
 1. A tibial implant for knee, the tibial implantcomprising: (a) a bulk implant; (b) a planar face defining an exteriorbone-engaging surface of the bulk implant, the exterior bone-engagingsurface sized and configured to contact a resected surface of a proximaltibia; (c) pillars for contacting a hard tissue, the pillars beingdistributed on the exterior bone-engaging surface, across an area of atleast 30 mm², and extending perpendicularly from the planar face, andeach pillar being integral to the bulk implant, having a distal end,having a transverse area of (100×100) μm²to (10,000 ×10,000) μm², andhaving a height of 100 μm to 10,000 μm; (d) slots to be occupied by thehard tissue, the slots being defined by the pillars and each slot havinga width of 100 μm to 10,000 μm as measured along the shortest distancebetween adjacent pillars; and (e) at least one support member forcontacting the hard tissue, the at least one support member beingpositioned on the exterior bone-engaging surface among the pillars,extending distally from the exterior bone-engaging surface, having atransverse area greater than the transverse area of any of the pillars,and having a height greater than the height of any of the pillars;wherein the tibial implant has a Young's modulus of elasticity of atleast 3 GPa, and has a ratio of (i) the sum of the volumes of the slotsto (ii) the sum of the volumes of the pillars and the volumes of theslots of 0.40:1 to 0.90:1; wherein: one or more pillars have dimensionsthat differ from those of other pillars, such that the transverse areasand/or heights, and thus volumes, of the one or more pillars differ fromthose of the other pillars; and the one or more pillars are distributedperipherally with respect to the exterior bone-engaging surface and areintended for insertion into cortical bone, and the other pillars aredistributed centrally with respect to the exterior bone-engaging surfaceand are intended for insertion into cancellous bone; and wherein thepillars are non-porous.
 2. The tibial implant for knee of claim 1,wherein the tibial implant for knee is made of one or more materialsselected from implantable-grade polyaryletherketone that is essentiallyunfilled, implantable-grade polyetheretherketone, implantable-gradepolyetherketoneketone, titanium, stainless steel, cobalt-chromium alloy,titanium alloy, Ti-6Al-4V titanium alloy, Ti-6Al-7Nb titanium alloy,ceramic material, silicon nitride (Si3N4), implantable-grade compositematerial, implantable-grade polyaryletherketone with filler,implantable-grade polyetheretherketone with filler, implantable-gradepolyetheretherketone with carbon fiber, or implantable-gradepolyetheretherketone with hydroxyapatite.
 3. The tibial implant for kneeof claim 1, wherein the tibial implant for knee is made of one or morehard tissues selected from human hard tissue, animal hard tissue,autologous hard tissue, allogenic hard tissue, xenogeneic hard tissue,human cartilage, animal cartilage, human bone, animal bone, cadaverbone, or cortical allograft.
 4. The tibial implant for knee of claim 1,wherein the tibial implant for knee is made of one or more materialsselected from resin for rapid prototyping, SOMOS® NanoToolnon-crystalline composite material, SOMOS ® 9120 liquid photopolymer,SOMOS® WaterShed XC 11122 resin, ACCURA® XTREME™ White 200 plastic, orACCURA® 60) plastic.
 5. The tibial implant for knee of claim 1, whereinthe face is flat.
 6. The tibial implant for knee of claim 1, wherein thetransverse area of each pillar is (250×250) μm² to (1,000×1,000) μm². 7.The tibial implant for knee of claim 1, wherein the height of eachpillar is 200 to 2,500 μm.
 8. The tibial implant for knee of claim 1,wherein the width of each slot is 200 to 2,500 μm.
 9. The tibial implantfor knee of claim 1, wherein the at least one support member is integralto the bulk implant.
 10. The tibial implant for knee of claim 1, whereinthe at least one support member comprises a support member axial surfacecomprising support member pillars extending therefrom.
 11. The tibialimplant for knee of claim 1, wherein the at least one support membercomprises a support member axial surface lacking pillars.
 12. The tibialimplant for knee of claim 1, wherein the bulk implant is non-porous. 13.The tibial implant for knee of claim 1, wherein the at least one supportmember is non-porous.